Study on Compaction Characteristics and Strength through Ultrasonic Method

Abstract

Over 130 tests were performed on three soils of Chennai, while studying experimentally the relation between pulse velocity, dry densit y, water content and compacting effort. Laboratory test specimens were prepared by static and dynamic compaction methods in CBR mould (150 mm dia.), Proctor mould (100 mm dia.) and split mould (38 mm dia.). P-wave velocity was measured on each of the compacted specimen by adopting the direct transmission method. Unconfined compressive tests were also conducted on compacted samples of 38 mm diameter to establish the relation between compressive strength and pulse velocity. All soils tested exhibited an increasing pulse velocity with increase in dry density until the optimum water content. A rapid drop in pulse velocity was observed subsequently with decrease in density irrespective of the type of soil, compaction method, energy of compaction and size of the specimen. The peak velocities and maximum densities were within ± 1 % variation of water content in all the compaction methods, irrespective of the soil type and compaction energies studied. This observation is in conformity with the findings of earlier inv estigators (Sheeran et al (1967) and Yesiller et al (2000)). Further the pulse velocity measured on the compacted soils was correlated with compaction density, compaction moisture content, strength and modulus, and sets of empirical relations among these parameters are presented for the soils tested. These equations are validated through a set of data obtained on another soil of Chennai.